Stainless steel and similar sterilizable tables are important for the food preparation industry. Such tables provide the necessary work surfaces for cleaning, cutting and assembling foods served to customers. Open table supports provide space for storage of materials used in the food preparation. Models with an undershelf provide additional storage space for bowls and containers. A typical commercial kitchen has use for both open and undershelf tables.
The basic version of an open table uses legs of a tubular or rectangular cross sectional shape that are inserted into mating sockets connected or welded to the underside of the table top. A set screw for each socket provides lateral pressure in the inserted table leg portion to hold the leg within the socket and provide a measure of stability. Greater stability for the table is provided with a support frame made of rigid tubes or bars that are welded between the legs. Similarly, an undershelf can be welded between the legs and serve as the lower support for the table legs.
Metal food preparation tables having all welded connections make for a very stable work surface but at increased cost and difficulty of transporting the unit from manufacturer to customer. Such tables must be shipped in a fully assembled state by large pallets or crates using special equipment that can handle the weight of the fully assembled table unit.
For convenience, transport to offsite events, or reduced shipping costs prep tables have been offered that can be disassembled for transport and reassembled on site. Such tables use an open socket and set screw to attach the legs to the table top. The open table models use a lower support frame in an “H” frame or “C” frame construction and pass-through ferrules of circular or rectangular shape at each corner. Lateral set screws on each ferrule are used to hold the leg in place.
The conventional undershelf for a prep table uses a connection configuration that is similar to those of the open support frame. In particular, the typical undershelf unit would exhibit a pass-through ferrule connection on each corner of the undershelf and set screws to hold the shelf in position on the legs. Unfortunately, the use of set screws and pass-through ferrules for either the open or undershelf models can loosen over time and commercial use so that the table becomes less stable and requires adjustments to all set screws.
The National Sanitation Foundation (NSF) a number of regulations regarding food preparation tables. The currently approved materials are certain types of stainless steel and aluminum alloys. The NSF regulations also mandate that there be no gaps over 1/32″ to prevent the growth of bacteria.
It would be desirable to have a knock down prep table that complies with the applicable NSF regulations and which can be readily disassembled for transport and still form a stable work surface when reassembled.
A number of published applications and patents have described connections for tubular joints. For example, U.S. Pat. No. 2,647,000 describes a transverse, permanent connection using a deformed, internally threaded, metal washer or rivet within the joining tube. A bolt extends through aligned openings in the joined tube and into the internally threaded connection of the deformed washer. The washer is initially deformed using a deformation tool that uses a compression anvil around an extended bolt. The anvil engages the edges of the walls of the deformable rivet and, upon advance of the threaded bolt, compresses the rivet walls until they engage and become secured by internal grooves of the joining tube. The tool is then removed leaving the rivet in place ready to receive the connecting bolt during assembly.
U.S. Pat. No. 2,799,519 also describes the use of transverse bolts and an internal rivet to connect tubular members with T-joints.
U.S. Pat. No. 2,950,015 describes a joint system for knock down racks made of joined tubular members. The connections use some members that are spot welded and others that employ frictional fits between tube sections having larger and smaller diameters. One disclosed set of such frictional fits provide an expanded member having an internal, recessed bolt that engages a nut recessed in the member of reduced diameter.
U.S. Pat. No. 4,444,125 describes a knock down work table made with tubular legs having external grooves at increments over the length of each leg. The lower shelf and optional C-shaped support rail have pass-through ferrules at the corners. A frustoconical collar washer having an internal rib engages a leg groove and supports the shelf or support rail by the interaction of the leg groove and internal collar washer rib. U.S. Pat. No. 6,068,143 uses a similar leg groove/collar washer ridge system for upright shelf systems.
U.S. Pat. No. 4,786,203 relates to a connector assembly for food preparation equipment. The assembly is designed to minimize the formation of exposed gaps with a series of threaded connector elements and a locking collar that secure the joining tube to a mating connector that is transversely bolted to the joined tube.
U.S. Pat. No. 4,952,092 describes a system for permanently connecting vertically aligned metal tubes and metal cross-member rails that uses a threaded bolt passing through the vertically aligned tubes and connects the cross-member rails with round plugs forced into bosses protruding from the rails. The rail ends are then welded to the vertical tubes.
It would be desirable to have a joint system for a knockdown table that would allow for assembly into a highly stable work surface that would remain stable over extended time and which is suitable for use in food preparation.
It would also be desirable to have a knockdown food preparation table that can be shipped in a compact, disassembled state and readily re-assembled by the customer to form a highly stable work surface that is suitable for use in food preparation.